Autobiographical recall triggers visual exploration

Autobiographical recall is thought to rely on the ability to generate a visual image of the remembered event. Neuropsychological studies suggest a relationship between deterioration in visual mental imagery and autobiographical distortions, while neuroimaging data similarly implicate visual brain areas in autobiographical recall. However, neither whether autobiographical retrieval is associated with visual exploration, or not. Our paper aimed to provide such evidence one way or the other. Using an eye tracking system, we recorded eye movements of 40 participants during autobiographical recall and during a control condition in which participants had to count aloud. In both conditions, the participants had to look at a blank screen while their gaze location was recorded by the eye-tracker. Autobiographical recall triggered a lower number of fixations and reduced their duration. In contrast, the number, duration, and amplitude of saccades increased compared to the control condition. Our data suggest that autobiographical recall is characterized by visual processing

Face or building superiority in peripheral vision reversed by task requirements

Peripheral vision has been the topic of few studies compared with central vision. Nevertheless, given that visual information covers all the visual field and that relevant information can originate from highly eccentric positions, the understanding of peripheral vision abilities for object perception seems essential. The poorer resolution of peripheral vision would first suggest that objects requiring large-scale feature integration such as buildings would be better processed than objects requiring finer analysis such as faces. Nevertheless, task requirements also determine the information (coarse or fine) necessary for a given object to be processed. We therefore investigated how task and eccentricity modulate object processing in peripheral vision. Three experiments were carried out requiring finer or coarser information processing of faces and buildings presented in central and peripheral vision. Our results showed that buildings were better judged as identical or familiar in periphery whilst faces were better categorised. We conclude that this superiority for a given stimulus in peripheral vision results (a) from the available information, which depends on the decrease of resolution with eccentricity, and (b) from the useful information, which depends on both the task and the semantic category

Influence des conditions de présentation sur les asymétries hémisphériques dans une tâche de comparaison de formes

Summary : Influence of the presentation conditions on hemispherie asymmetries in a form comparison task. The purpose of the present experiment was to examine the influence of the presentation conditions on the emergence of hemispherie asymmetries. Four groups were subjected to laterally presented meaningful and meaningless forms in a « same » / « different » judgment task concerning the orientation of the stimuli to be compared. The results show an interaction between the experimental conditions, determined by the duration of exposure, long (L) or short (C) of the reference stimulus and the presence (I) or absence (I) of an interstimulus interval (ISI), and the visual field of presentation. A short duration of exposure without ISI (CI condition) resulted in an advantage of the right hemisphere (RH) for « same » judgments. The increase of the presentation time (Ll condition) maintained the RH advantage but this time for « different » judgments. Additional processing time provided by the introduction of an ISI (LI condition) benefited more the left hemisphere (LH) than the RH. This condition led to a disappearance of laterality effects. Finally, the introduction of an ISI just after a brief presentation time (CI condition) degraded the performance. This degradation affected the early processed components of the visual display. This condition gave rise to a LH advantage. Reaction times were shorter for the meaningful than for the meaningless stimuli but no interaction was found between this factor and the visual field of presentation. The results are interpreted in terms of hemispheric asymmetries for global/local information processing. Key words : hemispheric asymmetries, form perception, global/local information processing.Résumé Cette expérience avait pour but de tester l'influence des conditions de présentation sur les asymétries hémisphériques. Quatre groupes de dix sujets ont été soumis à une tâche de jugements « identique » / « différent » portant sur l'orientation de formes « dénommables » et « non dénommables » présentées en hémichamp visuel. Les résultats font apparaître une interaction entre les conditions de présentation, déterminées par la durée d'exposition longue (L) ou courte (C) du stimulus de référence et la présence (I) ou l'absence (1) d'un intervalle interstimulus, et le champ visuel. Une durée d'exposition courte sans ISI (condition Cl) donne un avantage à l'hémisphère droit (HD) pour les jugements « identique ». Une augmentation de la durée d'exposition (condition Ll) maintient l'avantage de VHD mais cette fois pour les jugements « différent ». Une augmentation supplémentaire du temps de traitement fournie par l'introduction d'un ISI (condition LI) profite davantage à l'hémisphère gauche (HG) qu'à VHD et entraîne une disparition des effets de latéralité. Enfin, l'introduction d'un ISI après une durée de présentation brève (condition CI) dégrade la performance en affectant en premier lieu les composants de la stimulation visuelle traités précocement. Un avantage de l'HG est observé dans cette condition. Le temps de réaction des stimuli « dénommables » est plus court que celui des stimuli « non dénommables » mais ce facteur n'interagit pas avec le champ visuel de présentation. Les résultats sont interprétés en terme d'asymétrie hémisphérique pour le traitement des informations globales et locales. Mots clés : asymétrie hémisphérique, perception des formes, traitement global/local.Boucart Muriel. Influence des conditions de présentation sur les asymétries hémisphériques dans une tâche de comparaison de formes. In: L'année psychologique. 1989 vol. 89, n°2. pp. 255-275

TROUBLES DE L'ATTENTION DANS LA MALADIE D'ALZHEIMER. EXPLORATION A PARTIR D'UN TEST EVALUANT L'EFFET DE CLIGNEMENT ATTENTIONNEL AUPRES DE 18 PATIENTS

NANCY1-SCD Medecine (545472101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Imagined motor action and eye movements in schizophrenia

Visual exploration and planning of actions are reported to be abnormal in schizophrenia. Most of the studies monitoring eye movements in patients with schizophrenia have been performed under free-viewing condition. The present study was designed to assess whether mentally performing an action modulates the visuomotor behavior in patients with schizophrenia and in healthy controls.Visual scan paths were monitored in eighteen patients with schizophrenia and in eighteen healthy controls. Participants performed two tasks in which they were asked either to (1) look at a scene on a computer screen (free viewing), or (2) picture themselves making a sandwich in front of a computer screen (active viewing). The scenes contained both task-relevant and task-irrelevant objects. Temporal and spatial characteristics of scan paths were compared for each group and each task.The results indicate that patients with schizophrenia exhibited longer fixation durations, and fewer fixations, than healthy controls in the free viewing condition. The patients’ visual exploration improved in the active viewing condition. However, patients looked less at task-relevant objects and looked more at distractors than controls in the active viewing condition in which they were asked to picture themselves making a sandwich in moving their eyes to task-relevant objects on an image.These results are consistent with the literature on deficits in motor imagery in patients with schizophrenia and it extends the impairment to visual exploration in an action imagery task